http://www.washingtonpost.com/national/health-science/thunderstorms-contain-dark-lightning-invisible-pulses-of-powerful-radiation/2013/04/08/1c796ebc-8a76-11e2-a051-6810d606108d_story.html
"A lightning bolt is one of nature’s most over-the-top phenomena, rarely failing to elicit at least a ping of awe no matter how many times a person has witnessed one. With his iconic kite-and-key experiments in the mid-18th century, Benjamin Franklin showed that lightning is an electrical phenomenon, and since then the general view has been that lightning bolts are big honking sparks no different in kind from the little ones generated by walking in socks across a carpeted room. But scientists recently discovered something mind-bending about lightning: Sometimes its flashes are invisible, just sudden pulses of unexpectedly powerful radiation. It’s what Joseph Dwyer, a lightning researcher at the Florida Institute of Technology, has termed dark lightning." <more>
